renmember that
[tex] \sqrt[3]{ab}=( \sqrt[3]{a})( \sqrt[3]{b}) [/tex]
and
[tex] \sqrt[n]{x^m} =x^ \frac{m}{n} [/tex]
split it up
[tex] \sqrt[3]{-1(x-7)^4} =( \sqrt[3]{-1} )( \sqrt[3]{(x-7)^4}) [/tex]=
[tex](-1)((x-7)^ \frac{4}{3})=(-1)(x-7)(x-7)^ \frac{1}{3}=-(x-7) \sqrt[3]{x-7} [/tex]=
[tex](7-x) \sqrt[3]{x-7}=7\sqrt[3]{x-7}-x\sqrt[3]{x-7}[/tex]
